


Between Siblings

by thewinchesterlifestyle



Category: Supernatural
Genre: Age Difference, Anal Gaping, Barebacking, Bondage, Bottom Castiel, Butt Plugs, Castiel and Dean Winchester are Siblings, Castiel and Sam Winchester are Siblings, Castiel is a Winchester, College Student Sam, Dehumanization, Dildos, Dubious Morality, Exhibitionism, Fingering, Fucktoy Castiel, Gags, Incest, Loud Sex, M/M, Middle Sibling Sam Winchester, Objectification, Older Sibling Dean Winchester, Restraints, Rough Sex, Sam Has a Large Cock, Secret Relationship, Sexual Training, Sharing, Sibling Incest, Size Difference, Size Kink, Spreader Bars, Teen Castiel, Top Dean, Top Sam, Training, Underage - Freeform, Voyeurism, Younger Sibling Castiel (Supernatural), dubcon
Language: English
Status: Completed
Published: 2017-07-16
Updated: 2017-07-16
Packaged: 2018-12-02 17:19:04
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,523
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11513910
Author URL: https://archiveofourown.org/users/thewinchesterlifestyle/pseuds/thewinchesterlifestyle
Summary: It would be the very first time that Dean shared Castiel with someone; the first time he let anyone in on the sinful secret.





	Between Siblings

**Author's Note:**

> Written for several prompts.

Dean grinned down at the sight of his youngest brother. Castiel’s arms were bound tightly behind his back, his legs spread obscenely wide with an improvised spreader and his soft little mouth was stuffed gloriously full with a large red ball-gag. He lightly touched Castiel’s tiny cock and balls while he watched as Castiel whined and jerked.

It would be the very first time that he shared Castiel with someone, the first time he let anyone in on the sinful secret. Judging by the heated look in Sam’s eyes and the obvious erection Dean had been right that his other brother, the middle child of the family, would enjoy their sweet, trusting little brother.

He shifted Castiel to show off the obscenely large plug he had stuffed inside the tiny hole earlier.

“Wow.” Sam’s voice was rough, choked with arousal, as he stared and Dean smirked. He looked at Sam, pleased his brother had come back from college for break and that their parents were off on a second honeymoon while leaving Dean in charge of watching Castiel. “He’s…”

“A good little fucktoy.” Dean supplied as he stroked a hand along Castiel’s shaking back. “I’ve been training him up, breaking in that virgin ass and soft mouth. I hadn’t planned on it but once I tried him it was impossible not to use him again and again.”

The sound Sam made was almost strangled.

“I thought you might like to try him out…see how good he feels around your dick. The little slut makes a tight hole to fuck.”

Castiel whimpered as Dean kept touching him, shifting him again and moving to twist Castiel’s pink nipples. Their little brother jerked as best he could, face flushed and eyes glassy, as Dean twisted until they were a beautiful red.

His eyes idly took in the dry come at the corner of Castiel’s stretched mouth.

“Come on, Cas.” Dean breathed out lowly, “Let’s show your other big brother what a good dick-hungry slut you are.”

He shifted Castiel again and pulled him towards the edge of the bed so that Castiel’s plump, plug stuffed ass was offered up to Sam. Dean watched as Sam stepped forward and his surprisingly large hands spread Castiel’s round cheeks to offer his plugged hole up for viewing.

“Fuck, Cas…” Sam breathed out in appreciation. One of Sam’s hands moved, grabbed the end of the large plug and started lazily fucking Castiel’s ass with it. Muffled whimpers filled the room. “And you…you fuck him often?”

“As often as I can. Those moans you’ve heard whenever I visited? The ones that I know you thought were from someone I’d snuck in? When Mom and Dad were out or it was late at night? That was me pounding his little hole and training him to be a good, eager fucktoy. It's been a long and pleasurable road.”

"You started... _training_ him that early?"

"Of course. It's why he's so obedient and eager. You have to start training a fucktoy early for this kind of obedience."

Sam pulled the plug out and both of them admired the way Castiel’s small hole gaped lewdly. The choked whine when the plug had popped free had gone straight to Dean’s cock.

“Try him out…you’ll find yourself coming back for a weekend with a tight little hole for your use right under our parents’ roof. I’m sure he’ll be a good boy for you even when I’m not here.” What was left of Sam’s clothing ended up discarded on the floor and Dean watched as a surprisingly monster sized cock was freed.

Without much fanfare Sam started stroking himself to full hardness, coating his cock with lube, before stepping up to where Castiel was bent over, restrained and gagged in a beautiful position to be used.

* * *

He couldn’t believe that Dean had been keeping _this_ a secret for so many years. Castiel, soft and innocent little Castiel, frequently taking Dean’s cock without anyone knowing. Sam had known the second that Dean had explained that Castiel knew it was their secret that their little brother, who worshiped Dean and took his word as law, would take what was happening to the grave if Dean asked it.

It wasn’t surprising that Castiel had easily been guided into allowing Dean to fuck and use him. It was even less surprising considering how early Dean had apparently started training Castiel to take his cock. It really was wrong, so very very wrong how early he'd started, and Sam's arousal spiked unexpectedly at the thought. And it wasn’t, when he thought about it, surprising that Dean had decided to _share_ Castiel with _him_.

Dean had always been like that.

He gripped his hard cock and pressed the fat head against Castiel’s little lube slick hole, still invitingly gaping and waiting for a cock to fill it. Castiel’s body tensed as Sam started to push into perfect tight wet heat that delightfully squeezed him as his thick cock spread Castiel’s ass wide open.

A choked off cry, muffled by the large gag Dean had pushed into Castiel’s mouth after he’d finished face fucking their little brother in the living room when Sam had come home, escaped as Sam fucked forward. His fingers dug into Castiel’s soft hips right next to several sets of light bruises that would no doubt match Dean’s fingers.

Arousal burned inside of him and Sam knew his cheeks were flushed, his eyes hooded, as pleasure raced through him. He greedily watched his cock splitting Castiel’s ass open as he sunk inside and, slightly impatient, he slammed forward to bury himself balls deep with a loud, appreciative groan.

Castiel jerked, a soft sob escaping, as his hole viciously clamped down as it was abruptly spread open and filled.

“Doesn’t he feel good?” Dean asked as he moved around to get a better view of Castiel’s face. Sam remained balls deep, giving Castiel a few seconds to adjust to having his cock stuffed inside, before Sam rolled his hips back and snapped his hips forward to bury himself in once more.

“Fuck, Dean. He’s like a fucking vice.” He felt warm and on edge. It wasn’t often that he had sex with a guy but Castiel felt so good wrapped around him and whining as Sam started to viciously pound Castiel’s ass.

He could hear muffled whimpers and groans as he picked up the pace, the mattress creaking and groaning under the power behind his thrusts, while his balls loudly smacked up against Castiel’s ass.

Sam’s mouth fell open and his fingers dug in harshly, jerking him forward, as he fucked and fucked and fucked towards his orgasm. “Really give it to him, Sammy. Cas has been getting better at taking it rougher. A good fucktoy will take anything you give it. When I'm finished he'll be trained to do anything I want.”

One of his hands moved up, curled around where Castiel’s hands were bound behind his back, while his hips continued to quickly snap forward. Castiel’s ass rhythmically clenched as Sam fucked forward and Dean, at a glance, was watching with obvious interest in taking another turn with Castiel.

“So good, Cas.” Sam breathed out in appreciation, “Fuck…your hole feels so good.”

Castiel’s fingers curled and he could see, where Castiel’s head was turned and his face was in Dean’s general direction, that Castiel’s eyes were hooded and his face was flushed.

The mattress creaked louder as he started to vigorously fuck Castiel’s plump, tight ass. Eventually his pace started to fall off, still hard and fast as he chased his orgasm, until Sam slammed deep and came with a loud moan of enjoyment.

His hips jerked forward a few times, chasing the pleasure caused by the tight clench of Castiel’s ass, before he draped over Castiel and basked in the warmth of an orgasm. Both of them easily dwarfed Castiel, their little brother not yet getting his growth spurt, and Sam couldn’t help but enjoy the obvious size difference.

Castiel was smaller, soft and delightfully hot inside.

Sam eased back up off of Castiel and his soft cock slipped free. He took a moment to enjoy watching his come leak out of Castiel’s puffy, wrecked little hole. Sam spread Castiel’s cheeks apart again and admired the view, thumb hooking on Castiel’s rim and tugging as his little brother jerked and released a broken whine.

“How long have you—”

“Few years.” Dean shrugged as Sam blinked, “I was staying over for the holidays. It was late, I was horny and jerking off just wasn’t working. I was going to go out, pick someone up at a bar but I ran into Cas and…” Dean trailed off and he didn’t really need to explain because Sam knew what came next.

Their little brother losing his virginity to Dean’s quest to get off.

Sam moved out of the way as Dean stepped up, hand already jerking himself, as Castiel’s hole clenched around nothing. “See how greedy our slutty little brother is for dick?” Dean laughed and Sam watched as Dean didn’t even pause as he shoved himself inside Castiel. “I think he might have been born to be a good little fucktoy.”

Fingers curled in Castiel’s dark, unruly hair and shoved his face into the mattress as Dean immediately started fucking. Loud, filthy and appreciative moans filled the room as Dean started to rigorously pound Castiel’s sloppy ass without a care beyond pleasure.

The loud smack of skin against skin mixed with the creaks from the mattress as Castiel whined, whimpered and released little muffled sounds that had Sam twitching. He slipped out of the room to clean up but the very loud sounds of Dean fucking and thoroughly enjoying himself were more than obvious as he cleaned up.

He came back into the bedroom to the sight of Dean greedily fucking Castiel, telling him what a good little dick-hungry slut he was and how good he was at taking his big brothers’ cocks in his fuckable ass.

“My little fucktoy, aren’t you?” Dean’s voice was rough as he pounded forward and Castiel writhed under him. “So good at taking my dick. Always so good. You love making your big brother feel good, don’t you? Bet you’d love me to take you to one of those clubs where people share their partners. I’d cover you in black latex, gag your slutty mouth and plug your ass…then I’d have you bent over a fucking bench and let everyone in the club use you…they would have no idea that the slut they were fucking is such a young, pretty little thing.” Dean grinned in enjoyment and Sam knew the kind of clubs he was talking about. With Castel covered completely they would have no idea Castel was too young to be there. “You would like that, wouldn’t you? Want to take all of the dick in that greedy ass of yours just to make me happy, don’t you?”

He paused, balls pressed up against Castiel, as he leaned forward. Sam watched as Castiel jerkily nodded when Dean prodded him further and with a bright, pleased smile Dean stroked a hand down Castiel’s back in praise.

“Good fucktoy.” He breathed and started fucking again, fingers once more knotted in Castiel’s hair. “I’ll make sure to see if I can find a suit that will fit you. We’ll go early so more people can use you. I'll keep you in use from opening to closing."

Sam watched, feeling nothing but arousal at Castiel’s submission and compliance, as Dean manhandled him. He didn’t know how long he watched as Dean fucked Castiel until Dean was slamming deep, hips jerking forward, before a loud moan filled the room.

The creak from the mattress and the slap of skin absent.

Dean lazily fucked up against Castiel, cock now soft, as Sam watched and took in Castiel’s flushed face. “He’s really good at obeying you.” Sam idly commented as Dean pulled out and pushed his release back inside before more lube was added to his wet hole. Without answering him Dean reached for the plug and shoved it back inside Castiel’s ruined hole.

Castiel jerked as it pushed past his rim and a muffled wail escaped before it settled inside. The size of it was impressive, fist sized and thick. Sam would bet anything it ached where it spread Castiel’s little ass open.

Dean left the room as Sam started tugging his clothing back on and when Dean returned he pulled his own clothing on.

“Later let’s see how good he is at taking both of us together.” Dean finally commented as he freed Castiel from the improvised spreader bar but nothing else. He hauled Castiel up and started guiding their brother, still naked and trussed up, from the bedroom.

Sam watched as Castiel’s shaky legs carried him from the room, no protest or hint of disagreement with Dean’s guidance, as they moved towards the stairs. Dean hauled him up and moved down the stairs before leading the way into the living room.

He hung back and watched as Dean set things up, affixing a truly impressively large dildo to the coffee table. Castiel didn’t seem surprised by it but Sam could see a hint of hesitation in his blue eyes.

Dean removed the plug, helped Castiel up onto the table and then Castiel was being guided down until the large dildo impaled him on the table. Soft sounds of discomfort filled the room as Castiel took every single thick inch until his ass was pressed flat to the table.

“He knows why he’s spending a few hours on the table.” Dean spoke to Sam’s silent question of _why_ Dean was leaving their little brother like that. He picked up a length of cloth tied to one of the legs of the table and wrapped it around one of Castiel’s ankles.

When Dean was finished Castiel’s legs were spread wide and Sam could _see_ the dildo nestled inside of Castiel through the thin skin of his belly. Castiel’s eyes were glassy, his cheeks flushed and Sam watched how his muscles trembled at being so full.

“Now be a good boy while Sam and I watch the movie I rented.” Castiel was positioned in such a way that he didn’t block the TV, “Can you do that?” Castiel nodded, eyes on Dean, as Dean gave a sound of approval and stroked his fingers through Castiel’s hair. Then Dean easily dropped into a seat, sprawled and relaxed.

Sam gave himself a few more moments to enjoy the sight that Castiel presented before he took a seat of his own, sinking into the soft cushions and waiting for the movie. “Thanks for sharing him.” Sam finally voiced as Dean sighed as he relaxed further.

“Of course. I’m just glad you enjoyed him so much.” Dean’s eyes practically twinkled with amusement as Sam offered a grin. It might be wrong but he had honestly enjoyed himself.

He’d forgotten how good it felt to fuck a tight ass and Castiel had, truthfully, been very good at taking it.

**Author's Note:**

> I had several prompts wanting a Dean/Cas/Sam sibling fic with older siblings Dean/Sam topping/using Cas with a variety of kinks in each request. I tried to weave all of that together in this one. I wasn't given an age for Castiel in any of the prompts (though the ones that did wanted underage!Cas so I left it ambiguous on how much younger he is then Sam...Dean and Sam are still four years apart) but I have Sam about 19 in this one (one year into getting a degree).
> 
> I hope everyone asking for this kind of fic enjoyed this attempt to marry all of the requests together; let me know if you liked what I did with your prompt. Also this is my first time writing Sam/Cas so, once more, I hope I pulled it off. Feedback is _always_ appreciated :D
> 
>    
> Please leave a comment and let me know what you thought. Remember comments are motivation for continuing to write and post fanfics!


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